Method for diagnosing a vacuum actuator

ABSTRACT

Methods and systems are described for diagnosing degradation of a vacuum actuator in an engine system. An example method comprises indicating degradation of the vacuum actuator based on an estimate of flow of air into and out of a vacuum reservoir. The estimate is further based on flow of air generated via each of an aspirator in the intake system, an actuation of the vacuum actuator, and leakage during the actuation of the vacuum actuator.

TECHNICAL FIELD

The present application relates to evaluating a vacuum actuator based onavailable vacuum fill in a vacuum reservoir.

BACKGROUND AND SUMMARY

Vacuum may be used to operate or to assist in the operation of variousdevices of a vehicle. For example, vacuum may be used to assist a driverapplying vehicle brakes, fuel vapor purging, heating and ventilationsystem actuation, and actuation of various valves such as a wastegate, acharge motion control valve (CMCV), etc. CMCVs may be coupled upstreamof intake valves of engine cylinders in order to increase or decreasethe charge motion of a corresponding cylinder, thereby increasing ordecreasing the cylinder burn rate, respectively. Vacuum to actuate thesevalves may be obtained from an engine intake manifold in normallyaspirated engines because the intake manifold pressure is often at apressure lower than atmospheric pressure. When vacuum in the engineintake manifold is not sufficient, vacuum to actuate these valves may bereceived from a vacuum reservoir.

Diagnostic tests on vacuum actuated valves may be performedintermittently to identify degraded functionality. As an example,diagnostics may determine if a plate of the CMCV is stuck open (or stuckclosed) based on a response of a position sensor coupled to the CMCV. Ifthe position sensor does not indicate a change in position in responseto an actuation command, the functionality of an actuator of the CMCVmay be diagnosed as degraded. Accordingly, a diagnostic code may beflagged in a control system indicating a degraded actuator. However,diagnostic tests may incorrectly diagnose the vacuum actuator asdegraded when adequate vacuum is not available to actuate the vacuumactuator. As such, incorrect diagnoses may result in false diagnosticcodes being set which can lead to unnecessary testing and expenses.Overall, maintenance costs may increase leading to customerdissatisfaction.

The inventors herein have recognized the above issue and identified anapproach to at least partly address the issue. In one example approach,a method is provided to diagnose degradation of a vacuum actuator. Themethod comprises indicating degradation of the vacuum actuator based onan estimate of flow of air into and out of a vacuum reservoir, theestimate based on flow of air generated via each of an aspirator in theintake system, an actuation of the vacuum actuator, and leakage duringthe actuation of the vacuum actuator. Thus, incorrect diagnoses ofvacuum actuator degradation due to insufficient vacuum levels in thevacuum reservoir may be reduced.

For example, an engine may include one or more vacuum actuated CMCVspositioned in an intake passage downstream of an intake throttle andupstream of one or more intake valve(s) of cylinders. As such, the CMCVsmay be actuated by a vacuum actuator that may source vacuum from eitherthe intake manifold or a vacuum reservoir. During conditions whenmanifold vacuum is not adequate for actuating the CMCV(s), supplementaryvacuum may be drawn from the vacuum reservoir. The vacuum reservoir maybe fluidically coupled to each of the intake manifold of the engine, asuction port of an aspirator, and to one or more CMCVs. A total amountof vacuum fill in the vacuum reservoir may be estimated based on flow ofair into the vacuum reservoir and flow of air out of the vacuumreservoir. Air may flow into the vacuum reservoir when actuating theCMCVs, and air may flow out of the vacuum reservoir towards the intakemanifold and/or the suction port of the aspirator. If the amount ofvacuum fill in the vacuum reservoir is estimated to be lower than athreshold level, adequate vacuum may not be available to actuate theCMCV(s). Accordingly, if actuation of the CMCV(s) does not produce achange in a position sensor coupled to the CMCV(s), the control systemmay not indicate that the CMCV is degraded. On the other hand, if theamount of vacuum fill in the vacuum reservoir is higher than a thresholdlevel and actuation of the CMCV(s) does not produce a change in theposition sensor, the CMCV(s) may be determined to be degraded.

In this way, degradation of a vacuum actuator may be more accuratelydetermined based on estimating a total amount of vacuum fill in a vacuumreservoir coupled to the vacuum actuator. By determining that anavailable quantity of vacuum in the vacuum reservoir is lower than adesired quantity, non-responsiveness of the vacuum actuator may beattributed to a lack of vacuum in the vacuum reservoir. Accordingly,indications of vacuum actuator degradation during diagnostic routinesmay be diminished, particularly when vacuum fill in the vacuum reservoiris lower than desired. As such, diagnostic routines may be completedwithout a malfunction indicator light being actuated. This in turn mayreduce needless and costly diagnostics, and unnecessary maintenance frombeing carried out.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an engine.

FIG. 2 shows a schematic illustration of a single cylinder within theengine of FIG. 1.

FIG. 3 depicts an example flowchart for diagnosing degradation in avacuum actuator in the engine of FIG. 1, in accordance with the presentdisclosure.

FIGS. 4a and 4b present an example flowchart for estimating a volume ofair fill, and corresponding vacuum, in a vacuum reservoir in the engine,according to the present disclosure.

FIG. 5 shows an example flowchart illustrating an estimation of aninitial volume of air in the vacuum reservoir.

FIG. 6 depicts an example diagnosis of the vacuum actuator according tothe present disclosure.

DETAILED DESCRIPTION

The following description relates to systems and methods for determiningdegradation in a vacuum actuated valve, such as a charge motion controlvalve (CMCV), positioned in an intake of an engine system, such as theengine depicted in FIGS. 1 and 2. An actuator of the vacuum actuatedvalve may receive vacuum from either an engine intake manifold or avacuum reservoir. Degradation of the actuator and/or vacuum actuatedvalve may be indicated when the vacuum actuated valve does not changeposition upon actuation. However, an actuation command may not result ina corresponding change in valve position if sufficient vacuum is notavailable in the vacuum reservoir to actuate the valve. An amount ofvacuum fill in the vacuum reservoir may be modeled by estimating airflow into and out of the vacuum reservoir (FIGS. 4a, 4b , and 5). Adiagnosis of the vacuum actuated valve may be based upon the estimatedamount of vacuum fill in the vacuum reservoir (FIG. 3) such that thevacuum actuated valve is determined to be degraded only if the estimatedamount of vacuum fill is higher than a threshold amount (FIG. 6) andactuation does not produce a change in position of the vacuum actuatedvalve. In this way, an unresponsive vacuum actuated valve may not bedeemed as degraded if sufficient vacuum is not available for itsactuation.

FIG. 1 shows a schematic depiction of an example engine system 100including a multi-cylinder internal combustion engine 10. As onenon-limiting example, engine system 100 can be included as part of apropulsion system for a passenger vehicle. Engine 10 may be controlledat least partially by a control system 14 including a controller 12 andby input from a vehicle operator 132 via an input device 130. In thisexample, input device 130 includes an accelerator pedal and a pedalposition sensor 134 for generating a proportional pedal position signalPP.

Engine system 100 can receive intake air via intake passage 42. Intakepassage 42 can include an air filter (not shown). Engine 10 may includea plurality of cylinders 30. In the depicted example, engine 10 includessix cylinders arranged in a V-configuration. Specifically, the sixcylinders are arranged on two banks 13 and 15, with each bank includingthree cylinders. In alternate examples, engine 10 can include two ormore cylinders such as 3, 4, 5, 8, 10 or more cylinders. These variouscylinders can be equally divided and arranged in alternateconfigurations, such as V, in-line, boxed, etc. Each cylinder 30 may beconfigured with a fuel injector 66. In the depicted example, fuelinjector 66 is a direct in-cylinder injector. However, in otherexamples, fuel injector 66 can be configured as a port fuel injector.

Intake air supplied to each cylinder 30 (herein, also referred to ascombustion chamber 30) via common intake manifold 44 may be used forfuel combustion and products of combustion may then be exhausted viabank-specific exhaust passages. In the depicted example, a first bank 13of cylinders of engine 10 can exhaust products of combustion via acommon first exhaust manifold 56 through a common exhaust passage 17 anda second bank 15 of cylinders can exhaust products of combustion via acommon second exhaust manifold 48 through a common exhaust passage 19.

The intake passage 42 includes an intake throttle 62 having a throttleplate 64. In this particular example, the position of the throttle plate64 may be varied by controller 12 via a signal provided to an electricmotor or throttle actuator 67 included with the intake throttle 62, aconfiguration that is commonly referred to as electronic throttlecontrol (ETC). The intake passage 42 may include a mass air flow sensor120 and a barometric pressure sensor 121 for providing respectivesignals MAF and BP regarding air flow through the intake and barometricpressure respectively, to the controller 12. An aspirator 20 may becoupled in an aspirator passage 23 across intake throttle 62 as shown.When manifold pressure downstream of intake throttle 62 is lower thanair pressure upstream of intake throttle 62, air may enter the aspiratorpassage 23 at first end 27, flow through aspirator 20, and enter intakemanifold 44 at second end 29 of the aspirator passage 23. Air flowingthrough aspirator 20 may generate vacuum at the neck of aspirator 20which may draw air from one or more of a vacuum reservoir 158, a brakeaccumulator, a brake booster, a fuel vapor canister (not shown), etc.

A number of charge motion control devices (CMCD) 80 may be positioned inthe intake manifold 44, with each CMCD corresponding to one of cylinders30. As seen in FIG. 1, intake manifold 44 splits into individual,discrete paths corresponding to individual cylinders 30. Inside each ofthe discrete paths a CMCD 80 may be placed to manipulate airflow intothe corresponding cylinder. Thus, each of cylinders 30 may befluidically coupled to a single CMCD 80. Other embodiments may include asingle cylinder being fluidically coupled to multiple CMCDs 80 withoutdeparting from the scope of the present disclosure. In some embodiments,CMCDs 80 may include valves, such as shown in FIG. 1, in which case thedevices may be equivalently referred to as charge motion control valves(CMCV) 80. CMCV 80 may also be referred to as swirl control valves ortumble control valves.

CMCVs 80 may restrict airflow to one or more of cylinders 30 for avariety of desired results, including but not limited to adjustingturbulence and burn rate. In the example of FIG. 1, each CMCV 80 mayinclude a valve plate with a cut-out section. Other designs of the valveplate are possible. Note that for the purposes of this disclosure theCMCV is in the “closed” position when it is fully activated and thevalve plate may be fully tilted into the respective conduit of intakemanifold 44, thereby resulting in maximum air charge flow obstruction.Alternatively, the CMCV is in the “open” position when deactivated andthe valve plate may be fully rotated to lie substantially parallel withairflow (as depicted in FIG. 1), thereby considerably minimizing oreliminating airflow charge obstruction. The CMCVs may principally bemaintained in their “open” position and may only be activated “closed”when swirl conditions are desired. Each CMCV 80 may be adjusted via arotating shaft to rotate the valve plate so that the valve plate isparallel to the flow direction when in the “open” position. In otherembodiments, the valve (plate) of each CMCV 80 may be integrated intothe branches of intake manifold 44 such that airflow restriction iscaused by end-pivoting CMCV 80 into the airflow during the closedposition. Other configurations of CMCV 80 are possible while remainingwithin the scope of the present disclosure.

As shown in FIG. 1, CMCVs 80 in the first bank 13 of cylinders of engine10 may be rotated by rotating shaft 71 which may be actuated by actuator77. Likewise, CMCVs 80 in the second bank 15 of cylinders of engine 10may be rotated by rotating shaft 81 which may in turn be actuated byactuator 75. CMCV actuators 75 and 77 may be vacuum actuators and may befluidically coupled to vacuum reservoir 158 via respective conduits. Asupply of vacuum to CMCV actuators 75 and 77 may be provided viarespective conduits 97 and 98 based on activation of respective valves87 and 89. Vacuum may be obtained from vacuum reservoir 158, as shown inFIG. 1. Further, vacuum may also be received from the intake manifold 44(not shown in FIG. 1) which may be substantially under vacuum conditionsduring engine operation e.g. when the intake throttle 62 is closed ormostly closed. In one example, valves 87 and 89 may be solenoid valves.A change in position of the rotating shafts 71 and 81 may be determinedby respective position sensors 85 and 83 which may be coupled to theirrespective rotating shafts by one of several methods.

Engine system 100 may include a control system 14 which in turncomprises controller 12, which may be any electronic control system ofthe engine system or of the vehicle in which the engine system isinstalled. Controller 12 may be configured to make control decisionsbased at least partly on input from one or more sensors 16 within theengine system, and may control actuators 82 based on the controldecisions. For example, controller 12 may store computer-readableinstructions in memory, and actuators 82 may be controlled via executionof the instructions. Example sensors include MAP sensor 122, MAF sensor120, BP sensor 121, position sensors 83 and 85, and manifold airtemperature (MAT) sensor 123. Example actuators include throttleactuator 67, fuel injector 66, solenoid valves 87 and 89 that supplyvacuum to CMCV actuators 75 and 77 respectively, to adjust CMCVs 80,etc. Additional sensors and actuators may be included, as described inFIG. 2.

Control system 14 with controller 12 may include computer-readableinstructions for controlling actuators 82, in particular CMCV actuators75 and 77. For example, actuation (i.e., opening and closing) of CMCVs80 may be a function of engine speed and load, wherein load is afunction of factors such as intake manifold pressure (MAP), atmosphericpressure, and temperature, among others. In other examples, actuation ofCMCVs 80 may be responsive to actuation of intake throttle 62 and may beused within the control system to monitor engine load. Alternately, thecontrol system 14 may have instructions to close and/or open CMCV(s) 80in response to a function of both variables. Valve actuation may befurther responsive to temperature, ignition timing, or other conditionsnot otherwise specified.

Referring now to FIG. 2, it portrays one cylinder 30 of multi-cylinderengine 10 of the embodiment of FIG. 1. Cylinder 30 in FIG. 2 may be onecylinder from second bank 15 of cylinders of engine 10 in FIG. 1. Assuch, components previously introduced in FIG. 1 are numbered similarlyin FIG. 2 and not reintroduced.

Cylinder 30 (also termed combustion chamber 30) of engine 10 may includecombustion chamber walls 32 with piston 36 positioned therein. Piston 36may be coupled to crankshaft 40 so that reciprocating motion of thepiston is translated into rotational motion of the crankshaft.Crankshaft 40 may be coupled to at least one drive wheel of a vehiclevia an intermediate transmission system (not shown). Further, a startermotor may be coupled to crankshaft 40 via a flywheel (not shown) toenable a starting operation of engine 10.

As described earlier in reference to FIG. 1, combustion chamber 30 mayreceive intake air from intake manifold 44 via intake passage 42 and mayexhaust combustion gases via exhaust manifold 48 and exhaust passage 19.Intake manifold 44 and exhaust manifold 48 can selectively communicatewith combustion chamber 30 via respective intake valve 52 and exhaustvalve 54. In some embodiments, combustion chamber 30 may include two ormore intake valves and/or two or more exhaust valves.

In this example, intake valve 52 and exhaust valves 54 may be controlledby cam actuation via respective cam actuation systems 51 and 53. Camactuation systems 51 and 53 may each include one or more cams and mayutilize one or more of cam profile switching (CPS), variable cam timing(VCT), variable valve timing (VVT) and/or variable valve lift (VVL)systems that may be operated by controller 12 to vary valve operation.The angular position of intake and exhaust camshafts may be determinedby position sensors 55 and 57, respectively. Thus, the position of anintake cam may be determined by position sensor 55. The position of anexhaust cam may be determined by position sensor 57.

In alternative embodiments, intake valve 52 and/or exhaust valve 54 maybe controlled by electric valve actuation. For example, cylinder 30 mayalternatively include an intake valve controlled via electric valveactuation and an exhaust valve controlled via cam actuation includingCPS and/or VCT systems. While FIG. 2 depicts one cylinder 30 from secondbank 15 of cylinders in engine 10 of FIG. 1, other cylinders 30 of eachof first bank 13 and second bank 15 of engine 10 may similarly includeintake/exhaust valves controlled by one of the above described valveactuation systems.

Fuel injector 66 is shown coupled directly to combustion chamber 30 forinjecting fuel directly therein in proportion to the pulse width ofsignal FPW received from controller 12 via electronic driver 68. In thismanner, fuel injector 66 provides what is known as direct injection offuel into combustion chamber 30. The fuel injector may be mounted in theside of the combustion chamber or in the top of the combustion chamber,for example. Fuel may be delivered to fuel injector 66 by a fuel system(not shown) including a fuel tank, a fuel pump, and a fuel rail. In someembodiments, combustion chamber 30 may alternatively or additionallyinclude a fuel injector arranged in intake manifold 44 in aconfiguration that provides what is known as port injection of fuel intothe intake port upstream of combustion chamber 30.

Ignition system 88 can provide an ignition spark to combustion chamber30 via spark plug 92 in response to spark advance signal SA fromcontroller 12, under select operating modes. Though spark ignitioncomponents are shown, in some embodiments, combustion chamber 30 or oneor more other combustion chambers of engine 10 may be operated in acompression ignition mode, with or without an ignition spark.

Intake manifold 44 is shown communicating with intake throttle 62 havinga throttle plate 64. In this particular example, the position ofthrottle plate 64 may be varied by controller 12 via a signal providedto an electric motor or actuator (throttle actuator 67 not shown in FIG.2) included with intake throttle 62, a configuration that is commonlyreferred to as electronic throttle control (ETC). Intake throttle 62 maycontrol airflow from intake passage 42 to intake manifold 44 andcombustion chamber 30 among other engine cylinders. The position ofthrottle plate 64 may be provided to controller 12 by throttle positionsignal TP from throttle position sensor 58.

Exhaust gas sensor 126 is shown coupled to exhaust passage 19 upstreamof emission control device 70. Sensor 126 may be any suitable sensor forproviding an indication of exhaust gas air/fuel ratio such as a linearoxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), atwo-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or COsensor. Emission control device 70 is shown arranged along exhaustpassage 19 downstream of exhaust gas sensor 126. Device 70 may be athree way catalyst (TWC), NOx trap, various other emission controldevices, or combinations thereof.

As described in reference to FIG. 1, CMCV 80 is located in intakemanifold 44 in a conduit leading to intake valve 52 of cylinder 30. Aposition of CMCV 80 may be adjusted by rotating a shaft, such asrotating shaft 81 of FIG. 1, using CMCV actuator 75. The change inposition (or lack, thereof) of the rotating shaft and therefore, ofCMCVs 80, may be communicated via position sensor 83 to controller 12.When a change in position of the CMCV is desired, controller 12 mayactivate solenoid valve 87 to supply vacuum to actuate CMCV actuator 75.Vacuum may be provided to CMCV actuator 75 from vacuum reservoir 158.Vacuum reservoir 158 may provide vacuum exclusively to CMCV actuators asdepicted in FIG. 1. It will be noted that while the depicted schematicexamples of FIGS. 1 and 2 show vacuum reservoir 158 as located outsideof intake manifold 44, vacuum reservoir 158 may be positioned withinintake manifold 44. However, piping between the intake manifold and thevacuum reservoir may be externally situated. Vacuum may be drawn fromvacuum reservoir 158 only under conditions when manifold vacuum (vacuumin intake manifold 44) is not adequate for actuation of different vacuumactuators e.g. CMCV actuator 75. Accordingly, solenoid valve 87 may befluidically coupled via passage 99 and passage 95 to intake manifold 44.As such, vacuum levels in vacuum reservoir 158 may be replenished viapassage 95 from the intake manifold 44 (which will be described later)during engine conditions with increased intake manifold vacuum.Aspirator 20 may be coupled in passage 23 across from intake throttle 62such that a portion of air from upstream of intake throttle 62 may flowinto first end 27 of passage 23, through aspirator 20, and may exit intointake manifold 44 downstream of intake throttle 62. Air flow throughaspirator 20 creates a low pressure region within the aspirator 20,thereby providing a vacuum source for vacuum reservoirs and vacuumconsumption devices such as fuel vapor canisters, brake boosters, etc.Aspirators (which may alternatively be referred to as ejectors,venturis, jet pumps, and eductors) are therefore, passive devices whichcan provide low-cost vacuum generation when utilized in engine systems.

Continuing with FIG. 2, vacuum reservoir 158 may be supplied vacuum fromintake manifold 44 via passage 95. A check valve 60 is included inpassage 95 to allow a flow of air from vacuum reservoir 158 to intakemanifold 44 and inhibit flow of air from intake manifold 44 to vacuumreservoir 158. Air may be drawn from vacuum reservoir 158 when manifoldvacuum is higher than an amount of vacuum fill in vacuum reservoir 158.In other words, when manifold absolute pressure in intake manifold 44 islower than absolute pressure in the vacuum reservoir, air will flow fromvacuum reservoir into the intake manifold. Herein, the amount of vacuumfill in vacuum reservoir 158 will increase while simultaneously anamount of air fill in the vacuum reservoir 158 will decrease. It will beappreciated that a higher vacuum indicates a lower absolute pressure.

Additionally, vacuum reservoir 158 may be supplied vacuum from ejector20 via passages 91 and 73. Check valve 61 in passage 91 may allow a flowof air from vacuum reservoir 158 towards aspirator 20 and may impedeflow of air from the aspirator 20 to the vacuum reservoir 158. Further,ejector 20 may also supply vacuum to brake vacuum reservoir 138 which inthe depicted example communicates fluidically via passage 94 with brakebooster 140. Brake vacuum reservoir 138 may also be termed a brakeaccumulator. Brake vacuum reservoir 138 may receive vacuum fromaspirator 20 via passages 73 and 93. Check valve 63 in passage 93ensures air flows only from brake vacuum reservoir 138 to aspirator 20and that air does not flow from ejector 20 to brake vacuum reservoir138. Likewise, check valve 65 in passage 94 ensures air flows only frombrake booster 140 to brake vacuum reservoir 138, and does not pass frombrake vacuum reservoir 138 to brake booster 140. Brake booster 140 mayalso be provided vacuum directly from intake manifold 44 (not shown).Brake booster 140 may include an internal vacuum reservoir, and it mayamplify force provided by vehicle operator 132 via brake pedal 150 tomaster cylinder for applying vehicle brakes (not shown). Thus, it willbe noted that ejector 20 may provide vacuum to each of brake vacuumreservoir 138 and vacuum reservoir 158. Further, vacuum reservoir 158(and brake vacuum reservoir 138) may store lower pressure than manifoldpressure. As such, vacuum generated by aspirator 20 may bepreferentially provided to brake vacuum reservoir 138 since it suppliesvacuum to the brake booster 140. For example, check valve 63 may includea larger orifice relative to that included in check valve 61 to enable alarger proportion of aspirator generated vacuum to be supplied to brakevacuum reservoir 138. It will also be noted that vacuum reservoir 158may not be coupled to a pressure sensor. Accordingly, in order to learnan amount of vacuum fill level in the vacuum reservoir 158, anestimation model may be desired to determine the amount of vacuum filllevel that will be further described in reference to FIGS. 3-5.

Controller 12 is shown in FIG. 1 as a conventional microcomputerincluding: microprocessor unit 102, input/output ports 104, read-onlymemory 106, random access memory 108, keep alive memory 110, and aconventional data bus. Controller 12 commands various actuators such asthrottle plate 64, CMCV actuator 75 via solenoid valve 87, fuel injector66 and the like. Controller 12 is shown receiving various signals fromsensors coupled to engine 10, in addition to those signals previouslydiscussed, including: engine coolant temperature (ECT) from temperaturesensor 112 coupled to cooling sleeve 114; position sensor 134 coupled toan accelerator pedal 130 for sensing accelerator position adjusted byvehicle operator 132; a measurement of engine manifold pressure (MAP)from pressure sensor 122 coupled to intake manifold 44; a measurement ofbarometric pressure (BP) from pressure sensor 121 coupled to intakepassage 42; a measurement of vacuum in brake vacuum reservoir 138 frompressure sensor 125, a profile ignition pickup signal (PIP) from Halleffect sensor 118 (or other type) coupled to crankshaft 40; ameasurement of air mass entering the engine from mass airflow sensor120; position sensor 83 coupled to rotating shafts 81; and a measurementof throttle position from sensor 58. Engine position sensor 118 mayproduce a predetermined number of equally spaced pulses every revolutionof the crankshaft from which engine speed (RPM) can be determined.Storage medium read-only memory 106 in controller 12 can be programmedwith computer readable data representing instructions executable byprocessor 102 for performing the methods described below, as well asother variants that are anticipated but not specifically listed. Examplemethods and routines are described herein with reference to FIGS. 3-5.

In some embodiments, the engine may be coupled to an electricmotor/battery system in a hybrid vehicle. The hybrid vehicle may have aparallel configuration, series configuration, or variation orcombinations thereof. Further, in some embodiments, other engineconfigurations may be employed, for example a diesel engine.

It will be appreciated that though a single cylinder 30 is depicted inFIG. 2, each cylinder 30 in engine 10 may have its own set ofintake/exhaust valves, fuel injectors, spark plugs, etc. Also, in theexample embodiments described herein, the engine may be coupled to astarter motor (not shown) for starting the engine. The starter motor maybe powered when the driver turns a key in the ignition switch on thesteering column, for example. The starter is disengaged after enginestart, for example, by engine 10 reaching a predetermined speed after apredetermined time.

Thus, an example system may include an engine with a cylinder, thecylinder fluidically communicating with an intake passage via an intakemanifold, a charge motion control valve positioned in the intake passagedownstream of an intake throttle, an actuator that actuates the chargemotion control valve between an open position and a closed position, avacuum reservoir fluidically communicating with each of the actuator, anaspirator, and the intake manifold, and a controller withcomputer-readable instructions stored in non-transitory memory foractuating the charge motion control valve via the actuator.

Turning now to FIG. 3, it shows an example routine 300 for diagnosingdegradation in a vacuum actuated valve or a vacuum actuator, such as aCMCV or the CMCV actuator. Specifically, indication of degradation inthe CMCV actuator and/or CMCV is based upon an estimation of an amountof vacuum fill level in a vacuum reservoir that supplies vacuum to theCMCV actuator, such as vacuum reservoir 158 of FIGS. 1 and 2. Vacuumreservoir 158 may also be termed an intake manifold runner controlreservoir, and the CMCVs may also be termed intake manifold runnercontrol valves.

At 302, engine operating conditions may be determined. Engine operatingconditions may include engine speed (Ne), torque demand, combustionair-fuel ratio, barometric pressure (BP), manifold absolute pressure(MAP), etc. At 304, routine 300 may determine if conditions to estimatethe amount of vacuum fill level in the vacuum reservoir are met. Forexample, estimation the amount of vacuum fill in the vacuum reservoirmay not be implemented when manifold vacuum is sufficient to actuate theCMCV actuators. Thus, estimation of vacuum fill in the vacuum reservoirmay be performed when manifold vacuum is not sufficient to actuate theCMCV actuators, and when vacuum to actuate the CMCV actuators is beingsupplied by the vacuum reservoir.

If vacuum fill estimating conditions are not met, routine 300 continuesto 306 to not perform an estimation of reservoir vacuum, and ends. Onthe other hand, if vacuum fill estimation conditions are met, routine300 proceeds to 308 to estimate the amount of vacuum fill level (inother words, pressure) in the vacuum reservoir. Routine 400 of FIG. 4will provide further details regarding the estimation.

Next, at 310, routine 300 may determine if the estimated amount ofvacuum fill level in the reservoir, RV, (also termed reservoir vacuum)is less than a first threshold, Threshold_P. For example, the firstthreshold may be a vacuum of 7 inches of mercury. In another example,Threshold_P may be a vacuum of 6 inches of mercury. If it is determinedat 310 that the amount of vacuum fill level in the vacuum reservoir isless than Threshold_P, routine 300 continues to 312 to indicate a lowlevel of vacuum and to set a flag in the control system. As such, theamount of vacuum fill in the vacuum reservoir may be increased at thenext available opportunity. For example, if manifold vacuum is notsufficiently high to supply vacuum to the vacuum reservoir, and whenengine conditions permit, the intake throttle may be adjusted to a moreclosed position to increase manifold vacuum. The adjustment to theintake throttle may be accompanied by a corresponding rise in enginespeed to maintain engine power at a relatively constant level. As such,this method may be more suitable for vehicles equipped with continuouslyvariable transmission. In another example, air flow through theaspirator may be increased such that vacuum may be provided by theaspirator. Further, at 314, routine 300 may also set a flag to notactuate the vacuum actuator. In the example of CMCV actuators and CMCVs,the CMCV actuators may not be actuated so that the CMCVs may bemaintained in their open position and not be actuated to a closedposition.

If, at 310, it is determined that the amount of vacuum fill in thevacuum reservoir is greater than the first threshold, Threshold_P,routine 300 proceeds to 316 to store the estimated amount of vacuum fillreading in the controller. Further, when this estimation is followed bya subsequent actuation of the vacuum actuator (e.g. CMCV actuator),routine 300 may confirm at 318 that a corresponding position sensorindicates a change in position of the vacuum actuated valve, e.g.CMCV(s). If yes, routine 300 progresses to 320 to determine a robustactuator and/or a robust vacuum actuated valve. On the other hand, ifthe position sensor(s) does not indicate a change in position of thevacuum actuated valve (e.g. CMCV(s)) upon actuation of the vacuumactuators, e.g. CMCV actuators, at 322, routine 300 may determine thatthe actuator (or other related hardware) is degraded. Further, at 324, aflag may be set including a diagnostic code and a malfunction indicatorlamp (MIL) may be lit.

Thus, the example engine system described earlier may include acontroller with computer-readable instructions stored in non-transitorymemory for actuating the charge motion control valve via the actuator,e.g. CMCV actuator, and indicating degradation of the actuator if thecharge motion control valve remains motionless in response to theactuating when an amount of air fill in the vacuum reservoir is lowerthan a threshold. The amount of air fill in the vacuum reservoir isrelated to the amount of vacuum fill in the vacuum reservoir. Thus,degradation of the actuator may be indicated if the charge motioncontrol valve remains motionless in response to the actuating when theamount of vacuum fill in the vacuum reservoir is higher than athreshold, such as first threshold, Threshold_P. The controller mayfurther comprise instructions for disabling the actuator and the chargemotion control valve upon indication of degradation. The controller mayinclude further instructions for indicating low vacuum in the vacuumreservoir when the amount of air fill in the vacuum reservoir isestimated to be higher than the threshold (or when the amount of vacuumfill is lower than the first threshold, Threshold_P).

In this manner, by learning the amount of vacuum fill level in thereservoir, a more reliable determination of degradation in a vacuumactuator may be made. As such, upon actuation, an absence of acorresponding change in position of the CMCV(s) or other vacuum actuatedcomponents may be due to insufficient vacuum in the reservoir. The abovemethod, therefore, does not rely on simply a lack of responsiveness fromthe vacuum actuator to determine degradation.

Turning now to FIGS. 4a and 4b , they show routine 400 illustrating amethod for determining an amount of (or a volume of) vacuum fill levelin the vacuum reservoir. As such, the routine estimates an amount of airfill in the reservoir and calculates the amount of vacuum fill from theamount of air fill. Specifically, flow of air into and out of the vacuumreservoir is estimated based upon flow of air generated via each of anaspirator in the intake system, an actuation of a vacuum actuator, andleakage during the actuation of the vacuum actuator. Further, air fillin the vacuum reservoir may be used to determine a reservoir absolutepressure and then, a reservoir vacuum. It will be appreciated that thedescribed calculation of determining vacuum utilizes volume of air flowinstead of mass of air flow for ease of calculations. Mass flowcalculations may be used without departing from the scope of thisdisclosure.

At 402, routine 400 may determine if manifold absolute pressure (MAP) ishigher than a previously estimated reservoir absolute pressure (RAP).For example, RAP may be the most recent estimation that may be stored inthe memory of the controller. As described earlier in reference to 304of routine 300, MAP being higher than RAP may indicate that manifoldvacuum is not adequate to actuate vacuum actuators in the engine system.Further, during conditions when the pressure in the intake manifold(MAP) is not sufficiently low, vacuum to actuate the CMCV actuators maybe supplied by the vacuum reservoir, such as vacuum reservoir 158.

In another example, an entry condition to activate routine 400 may beconfirming that manifold vacuum, as estimated by a difference betweenbarometric pressure (BP) and MAP (as in, BP−MAP), is lower than a secondthreshold, Threshold_V. A lower manifold vacuum may indicate a higherabsolute pressure in the manifold. In other words, a lower level ofvacuum includes a smaller amount (or volume) of vacuum fill. Further, ahigher vacuum in the intake manifold indicates a lower pressure(absolute) in the intake manifold. Further still, a higher vacuumindicates a higher level of vacuum fill. Thus, when manifold vacuum(e.g. BP−MAP) is lower than the second threshold, Threshold_V, manifoldvacuum may not be sufficient to actuate the vacuum actuators such asCMCV actuators. In one example, Threshold_V may be 7 inches of mercury.In another example, Threshold_V may be 5 inches of mercury. As anexample, MAP may be higher than RAP (or manifold vacuum may be lowerthan Threshold_V) during high acceleration conditions when the intakethrottle (such as intake throttle 62 of engine 10) is in a wide openposition. In another example, manifold pressure may rise at lower enginespeeds with a mostly open intake throttle and thus, manifold vacuum maynot be adequate to actuate vacuum actuators.

If, at 402, it is confirmed that MAP is not higher than the previouslyestimated RAP (or that BP−MAP is not lower than Threshold_V), routine400 continues to 404 to not estimate or model the amount (or volume) ofair fill in the vacuum reservoir. Further, at 405, routine 400 may clearprevious estimates of flow of air into the vacuum reservoir due toactuations of the vacuum actuator including air flow due to leakage,from the controller memory. Further still, routine 400 sets RAP equal tothe measured MAP, and then ends. As such, since MAP is not higher thanthe previously estimated RAP, vacuum may be supplied from the intakemanifold to the vacuum reservoir resulting in a change in the volume ofvacuum fill in the vacuum reservoir. Therefore, the RAP may be updatedat 405 to be equal to MAP.

If it is determined at 402 that MAP is greater than the previouslyestimated RAP (or that BP−MAP is lower than Threshold_V), routine 400proceeds to 406 to retrieve an initial air fill volume in the vacuumreservoir (V_init) from memory. Routine 500 of FIG. 5 may be used todetermine an initial volume of air in the vacuum reservoir. The initialair volume in the vacuum reservoir may be a normalized volume. Bynormalizing air volume, the method described below for determiningvacuum in the vacuum reservoir may compensate for altitude. As such,vehicle altitude may affect manifold pressure and reservoir vacuum.

Next, at 408, an amount of air flow into the reservoir may be estimatedbased on a number of successive actuations (N) of the vacuum actuatorwhen MAP is lower than RAP (or when manifold vacuum is lower thanThreshold_V). For example, when manifold vacuum is not sufficient toprovide vacuum to the vacuum actuator, such as CMCV actuators 75 and 77of engine 10, vacuum reservoir 158 may supply vacuum to the vacuumactuators. Each actuation of the vacuum actuator may increase air fillin the vacuum reservoir, and simultaneously reduce vacuum fill in thevacuum reservoir. By counting the number of actuations (N) that depletevacuum from the vacuum reservoir, total volume of air flow (AF)introduced into the reservoir with N actuations may be calculated.Specifically, total volume of air flow, AF, into the vacuum reservoirwith N actuations of the vacuum actuator may be calculated bymultiplying N by a volume of air flow into the vacuum reservoir peractuation of the vacuum actuator (V_AF) as shown at 410.

A priori knowledge of the volume of air flow into the vacuum reservoirwith each actuation of the vacuum actuator, V_AF, may be calibratedon-bench. When on-bench, the engine may be shut down after confirmingthat the vacuum reservoir contains a certain vacuum fill. The certainvacuum fill may be such that a given number of actuations of the vacuumactuator are possible. As such, confirmation that the vacuum reservoiris under vacuum may be performed by using a pressure sensor coupled tothe vacuum reservoir when on-bench. The pressure sensor may indicate thepressure in the vacuum reservoir at the start of the calibration.Further, the engine may be at rest when shut down and the vehicle may bein an engine-off condition. After engine-off, the vacuum actuator (e.g.CMCV actuator) may be actuated successively (and counted) until there isno change in the position sensor output, indicating that actuation doesnot produce a change in the vacuum actuated valve. Next, existingpressure in the vacuum reservoir following the successive actuations(e.g. S number of actuations) may be determined via the pressure sensorcoupled to the vacuum reservoir. During engine-off, manifold vacuum maynot be present, and actuation of the vacuum actuator may draw vacuumonly from the vacuum reservoir. Specifically, actuation of the CMCVactuators to change the position of CMCVs may utilize vacuum only fromvacuum reservoir 158 of FIGS. 1 and 2. Thus, the volume of air flow peractuation may be calibrated by observing the number of actuationspossible (e.g. S) with engine-off that deplete the vacuum in the vacuumreservoir. Herein, the change in pressure in the vacuum reservoir afterthe successive actuations may be divided by the counted number ofactuations, e.g. S, to estimate V_AF at 412. Therefore, total volume ofair flow, AF, may be calculated as follows:

AF=N actuations*V_AF  (1)

After determining total volume of air flow, AF, into the vacuumreservoir, routine 400 continues to 414 to estimate a leakage volume ofair. During activation of the CMCV actuator, additional air flow mayleak into the vacuum reservoir. To elaborate, during an actuation of theCMCV actuator, vacuum may flow from vacuum reservoir 158 to vacuumactuator 75 through passage 97. As such, air may be drawn into thevacuum reservoir during the actuations. Passage 97 (and similarpassages) may be fashioned from hoses or similar conduits and vacuum mayfill these hoses. Further, vacuum may fill space adjacent to a diaphragmin the CMCV actuator. As such, couplings and joints between the passages(or hoses) and actuators, and passages and the vacuum reservoir mayinclude small leaks. Since the passages are filled with vacuum onlyduring actuation of the vacuum actuator, the leakage rate may only bemodeled during actuation of vacuum actuated valves.

Leakage air flow (LF) into the vacuum reservoir may be based on a totalduration of N actuations and a pre-determined leakage rate (LR) as shownat 416. To elaborate, an accumulated time of activation of the vacuumactuator during the N actuations may be tracked to determine the totalduration of N actuations. Further, leakage rate, LR, may be learned apriori on-bench similar to the calibration of V_AF. The engine may beshut down and at rest in an engine-off condition after confirming thatvacuum is present in the vacuum reservoir. Further, the pressure in thevacuum reservoir may be learned before the calibration by the pressuresensor coupled to the vacuum reservoir. Next, a sustained actuation ofthe vacuum actuator may be performed, at 418, and a duration of theactuation may be measured until vacuum in the vacuum reservoir isdrained. The pressure sensor may sense an existing pressure in thevacuum reservoir at the end of the calibration and a change in pressurein the vacuum reservoir from beginning of calibration until the end maybe estimated. Leakage rate, LR, may be estimated by dividing the vacuumreservoir pressure change by duration of the sustained actuation todeplete the reservoir. Thus, leakage air flow (LF) into the vacuumreservoir during N actuations may be determined by multiplying theaccumulated time of N actuations and leakage rate (LR).

LF=accumulated time of N actuations*LR  (2)

Next, an outflow of air from the reservoir towards an aspirator, such asaspirator 20 of engine 10, may be calculated. At 420, it may be firstconfirmed if the engine is ON and manifold vacuum is greater than athird threshold, Threshold_A. As mentioned earlier, manifold vacuum maybe determined as a difference between barometric pressure and manifoldabsolute pressure (e.g. BP−MAP). The aspirator coupled across the intakethrottle may generate a vacuum based on an existing air flow in theintake passage. Further, air flow in the intake passage of the enginemay occur when the engine is ON and intake manifold is at a lowerpressure than atmospheric pressure (as measured by BP). Further still,the aspirator may generate sufficient vacuum only when the differencebetween manifold pressure and atmospheric pressure is at leastThreshold_A. In one example, Threshold_A may be 3 inches of mercury. Inanother example, Threshold_A may be 4 inches of mercury. If, at 420, itis confirmed that the engine is ON and BP−MAP is higher than the thirdthreshold, Threshold_A, routine 400 continues to 422 to estimate an airflow (EF) out of the vacuum reservoir towards the ejector. To elaborate,vacuum generated by the aspirator may draw air from the vacuum reservoirinto the aspirator, and thereon into the intake passage. Thus, vacuumfill level in the vacuum reservoir may be increased due to aspiratorvacuum.

Air flow out of the vacuum reservoir due to ejector vacuum, EF, may becalculated based on a duration that the aspirator supplies vacuum to thevacuum reservoir for the CMCV, such as vacuum reservoir 158, a suctionflow rate of the aspirator, and air flow out of the brake accumulator orbrake vacuum reservoir that supplies the brake booster, such as brakevacuum reservoir 138 coupled to engine 10. At 424, EF may be calculatedby subtracting air flow from the brake vacuum reservoir that suppliesthe brake booster (brake accumulator) A_(BB) from a product of theduration that the aspirator supplies vacuum and the suction flow rate(SFR) of the aspirator.

EF=(duration of ejector action*SFR)−A _(BB)  (3)

Since aspirator 20 in the engine embodiment of FIG. 2 provides vacuum toeach of vacuum reservoir 158 and brake vacuum reservoir 138, vacuumgenerated at aspirator 20 may be shared by both reservoirs. Thus, in theduration that the aspirator supplies vacuum, air drawn from brake vacuumreservoir 138 (or vacuum supplied to brake vacuum reservoir 138) may notbe included, and therefore, subtracted, in the estimation of air fill invacuum reservoir 158 that supplies vacuum to CMCV actuators. Air flowfrom brake vacuum reservoir 138 (or brake accumulator) may be measuredat 426 by a pressure sensor, such as pressure sensor 125 in FIG. 2,coupled to brake vacuum reservoir 138. Routine 400 then proceeds to 432.

Returning now to 420, if routine 400 determines that the engine is notON and that manifold vacuum (as determined by BP−MAP) is lower thanThreshold_A, the aspirator may not be generating sufficient vacuum. Inone example, the engine may be in an engine-off condition with theengine shut down and at rest. If manifold vacuum is lower thanThreshold_A, adequate air flow may not be present in the intake, andthereby, no or low vacuum may be generated by the aspirator. However,any vacuum generated by the ejector and supplied to the vacuum reservoir158, EF, (as estimated at 424 by equation 3) before engine-off, orbefore manifold vacuum level decreased below Threshold_A, may beretained in the memory of the controller at 428, and further estimationof EF may be stopped at 430. Routine 400 then continues to 432.

Next, at 432, the total volume of air fill in the vacuum reservoir,V_RF, is calculated by combining initial air fill, V_init, air flow intovacuum reservoir due to successive N actuations, AF, leakage air flowinto the vacuum reservoir during the N actuations, LF, and bysubtracting air flow out of the vacuum reservoir due to ejector vacuum,EF. Thus,

V_RF=(V_init+AF+LF)−EF  (4)

Herein, EF may be a value retained in the memory of the controller at428. V_RF, if determined to be less than zero, may be clipped to beequal to zero, since zero volume of air fill may indicate a perfectvacuum.

At 434, reservoir absolute pressure (RAP) may be determined as follows:

RAP_new=BP*(V_RF/Reservoir volume)  (5)

Reservoir volume may be the actual volume of the entire vacuumreservoir, such as vacuum reservoir 158 of FIGS. 1 and 2. RAP_new mayreplace the previously estimated RAP in the memory of the controlsystem. Further, vacuum in the vacuum reservoir (RV) may be estimated bysubtracting RAP_new from BP, at 436.

RV=BP−RAP_new  (6)

RV may indicate the amount of vacuum fill in the vacuum reservoir

It will be appreciated that estimation of reservoir vacuum may beterminated when manifold vacuum increases above Threshold_V.Alternatively, the calculation of reservoir vacuum may be terminatedwhen manifold pressure reduces below a previous estimation of reservoirpressure (e.g. MAP<RAP). To elaborate, when manifold vacuum (BP−MAP) issufficient to supply vacuum to, and actuate, the vacuum actuators,manifold vacuum may be higher than reservoir vacuum. Therefore, theintake manifold may provide vacuum to the vacuum reservoir and mayaffect calculations of the RAP. Accordingly, when it is determined thatmanifold vacuum (BP−MAP) is higher than Threshold_V, RAP calculationsmay be aborted and cleared in the memory of the controller. Further, apreviously determined RAP may also be cleared from the memory and aninitial air fill may be determined as will be explained in reference toroutine 500 of FIG. 5 below.

In this way, vacuum in a vacuum reservoir may be modeled by estimatingan amount or volume of air flowing into and out of the vacuum reservoirdue to one or more actuations of the vacuum actuator, leakage flow,and/or aspirator vacuum. An initial, existing volume of air may bedetermined first, as will be detailed in FIG. 5, and air flow into thevacuum reservoir due to actuation(s) of the vacuum actuator andcorresponding leakage flow (if present) may be added. Further, ifaspirator vacuum is provided to the vacuum reservoir during theestimation, the quantity of air flow out of the vacuum reservoir may besubtracted. The quantity (or volume) of outflow of air from the vacuumreservoir due to aspirator vacuum may be based on vacuum supplied toother devices such as brake accumulator or brake vacuum reservoir 138 ofFIG. 2. The air fill in the vacuum reservoir may then be converted to anabsolute pressure, which may then be converted to a vacuum in thereservoir (RV). As such, this may be termed vacuum fill in thereservoir. Further, as described in FIG. 3, the estimated reservoirvacuum may be compared to a desired first threshold (Threshold_P). Ifthe estimated reservoir vacuum is lower than the desired firstthreshold, the controller may set a flag to replenish vacuum in thevacuum reservoir when an opportunity is determined. If reservoir vacuumis determined to be higher than the desired first threshold, and asubsequent actuation of the vacuum actuator does not produce a change inposition of the actuated valve (e.g. CMCV), degradation in the vacuumactuator (and/or vacuum actuated valve) may be determined.

Thus, an example method may comprise indicating degradation of a vacuumactuator based on an estimate of flow of air into and out of a vacuumreservoir, the estimate based on flow of air generated via each of anaspirator in the intake system, an actuation of the vacuum actuator, andleakage during the actuation of the vacuum actuator. Degradation of thevacuum actuator may be indicated when vacuum fill in the vacuumreservoir based on the estimate of flow of air is higher than a firstthreshold (e.g. Threshold_P) and when a position of the vacuum actuatordoes not change when actuated. Further, the method may include notindicating degradation of the vacuum actuator when vacuum fill in thevacuum reservoir based on the estimate of flow of air is lower than thefirst threshold (e.g. Threshold_P) and when the position of the vacuumactuator does not change when actuated. The vacuum reservoir may be anintake manifold runner control reservoir, such as vacuum reservoir 158of FIGS. 1 and 2, which supplies vacuum only to the charge motioncontrol valve (CMCV) actuators. Further, the vacuum actuator may actuatea CMCV. The aspirator coupled in an engine system may draw air from thevacuum reservoir, the actuation of the vacuum actuator may flow air intothe vacuum reservoir, and leakage during the actuation of the vacuumactuator may introduce air into the vacuum reservoir. The flow of airvia the actuation of the vacuum actuator may be based on a calibratedvalue, the calibrated value being a first portion of air flowing intothe vacuum reservoir per actuation of the vacuum actuator. The flow ofair via leakage during the actuation of the vacuum actuator may be basedon a leakage rate, the leakage rate determined by calculating a secondportion of air flowing into the vacuum reservoir over a given durationduring sustained actuation of the vacuum actuator. The flow of air viathe aspirator may be a function of each of manifold vacuum (which maydetermine air flow rate in the engine intake passage) and vacuumconsumed by one or more vacuum consumption devices other than the vacuumactuator. The vacuum consumption devices may include one or more of areservoir supplying a brake booster such as a brake accumulator, thebrake booster, and a fuel vapor canister. Turning now to FIG. 5, itdepicts routine 500 illustrating the estimation of an initial normalizedair volume in the vacuum reservoir. The initial air fill volume isestimated prior to calculating changes in air fill in the vacuumreservoir. As explained earlier, the volume is normalized to accommodatefor vehicle altitudes.

At 502, routine 500 determines if pressure in the intake manifold (MAP)is lower than a previously estimated RAP. Alternatively, initial airvolume in the vacuum reservoir may be determined when manifold vacuum(e.g. BP−MAP) is higher than the second threshold, Threshold_Vintroduced in routine 400. An initial air fill volume of the vacuumreservoir may be determined when manifold vacuum is sufficient to supplyvacuum to the vacuum reservoir. When BP−MAP is greater than Threshold_Vand/or when MAP is less than the previously estimated RAP, air will flowfrom the vacuum reservoir to the intake manifold and a level of vacuumfill in the vacuum reservoir may increase. As mentioned earlier,Threshold_V may, in one example, be 7 inches of mercury. In anotherexample, Threshold_V may be 5 inches of mercury. As such, when MAP islower than RAP and/or when manifold vacuum is higher than Threshold_V,the controller may re-initialize the calculation of initial air fill inthe vacuum reservoir to determine a current air fill level.

If it is determined that MAP is lower than RAP and/or manifold vacuum ishigher than Threshold_V, routine 500 proceeds to 504 to estimate theinitial normalized air volume in the vacuum reservoir (V_init) asfollows: Reservoir volume*(MAP/BP). This estimated initial air volumemay be stored in the memory of the controller, at 506, for retrievalwhen a reservoir vacuum calculation (e.g. routine 400) is activated.

If, at 502, it is determined that MAP is not lower than the previouslyestimated RAP and/or manifold vacuum is lower than Threshold_V, routine500 continues to 508. In one example, MAP may be higher than thepreviously estimated RAP during high acceleration conditions when theintake throttle is wide open. In another example, MAP may be higher thanthe previously estimated RAP (or manifold vacuum may be lower thanThreshold_V) if the engine is shut down and at rest in the engine-offcondition. Herein, MAP may be equal to atmospheric (or barometric)pressure. Accordingly, at 508, routine 500 determines if the engine isin an engine-off condition and if the duration of engine soak is morethan Threshold_D. If the engine is shut down and at rest in theengine-off condition (also termed, engine soak) for a duration longerthan Threshold_D, reservoir vacuum may be depleted. As an example,reservoir vacuum may be depleted due to leakage. On the other hand, ashorter duration of engine soak may retain a portion of vacuum fill inthe vacuum reservoir. In one example, Threshold_D may be 3 days. Inanother example, Threshold_D may be shorter, e.g. 2 days. Alternatively,Threshold_D may be longer than 3 days.

If, at 508, routine 500 determines that the engine has been in theengine-off condition and the engine soak time is shorter thanThreshold_D, routine 500 proceeds to 509 where a new initial air volumemay not be calculated and at 510, a previously estimated initial airvolume may be retained in the memory of the controller. Routine 500 maythen end. On the other hand, if it is determined that the engine hasbeen in the engine-off condition and the engine soak time is greaterthan Threshold_D, routine 500 continues to 512. At 512, reservoir vacuumis estimated to be depleted and V_init may be determined to be equal toreservoir volume. To elaborate, if duration of engine soak is longerthan Threshold_D, MAP may be equal to BP. Therefore, calculating V_initaccording to the equation used in 504 (V_init=Reservoir volume*(MAP/BP))results in V_init being equal to reservoir volume. Routine 500 thenends.

Thus, in one representation, a method for estimating air fill in avacuum reservoir, may comprise determining an initial volume of air inthe vacuum reservoir, adding a first volume of air based on a number ofsuccessive actuations by a vacuum activated actuator, adding a secondvolume of air based on leakage during the number of successiveactuations, subtracting a third volume of air based on withdrawal of airfrom the vacuum reservoir by an aspirator, and indicating degradation ofthe vacuum activated actuator when the estimated air fill is lower thana threshold and a position of the vacuum activated actuator does notchange when actuated. The initial volume of air in the vacuum reservoirmay be determined when manifold absolute pressure is lower than apreviously estimated absolute pressure in the vacuum reservoir. Inanother example, the initial volume of air in the vacuum reservoir maybe determined when manifold vacuum is higher than a second threshold,such as Threshold_V. Further, the adding and subtracting may beperformed only when manifold vacuum is smaller (lower) than the secondthreshold Threshold_V. In other words, the initial air volume in thevacuum reservoir may be determined only when the intake manifold cansupply vacuum to the vacuum actuator(s) and vacuum reservoir, andreservoir vacuum may be estimated only when the intake manifold cannotsupply vacuum to the vacuum actuators and the vacuum reservoir. Furtherstill, reservoir vacuum may be estimated when the vacuum reservoir cansupply vacuum to the vacuum actuator(s). Additionally, the estimating ofair fill in the vacuum reservoir may accommodate for changes in vehiclealtitude by using a normalized initial volume of air in the vacuumreservoir.

FIG. 6 depicts map 600 illustrating an example diagnosis of a vacuumactuated valve (such as a CMCV) or a vacuum actuator, such as either ofCMCV actuators 75 and 77 of FIG. 1, based on the vacuum fill level inthe vacuum reservoir coupled in an engine. Map 600 includes a diagnosisof degraded vacuum actuator (or the vacuum actuated valve) at plot 602,a change in position sensor at plot 604, actuation of the vacuumactuator at plot 606, reservoir vacuum at plot 608 (dashed line),manifold vacuum at plot 610, engine load at plot 612, and engine speedat plot 614. All the above are plotted against time on the x-axis, andtime increases from the left of map 600 to the right of map 600. Line607 represents the first threshold for vacuum, such as first thresholdThreshold_P, and line 609 represents the second threshold for vacuum,such as Threshold_V. It will be noted that the example diagnosis showsvariations in manifold vacuum and reservoir vacuum, not manifoldpressure and reservoir pressure. As such, when manifold vacuum is lowerthan reservoir vacuum, manifold absolute pressure (MAP) is higher thanreservoir absolute pressure (RAP). Likewise, when manifold vacuum ishigher than reservoir vacuum, MAP is lower than RAP. Thus, a higherlevel of vacuum indicates substantially lower pressures, e.g. a lowerabsolute pressure. It will also be noted that though the first threshold(Threshold_P) and the second threshold (Threshold_V) are depicted hereinas separate thresholds, in some examples, these thresholds may be thesame. For example, each of Threshold_P and Threshold_V may be 7 inchesof mercury. In another example, both the first threshold and the secondthreshold may be 8 inches of mercury.

Prior to t1, the engine may be at idle as indicated by plot 614, andtherefore, engine load may be lower. At idle, manifold vacuum (plot 610)may be higher since the intake throttle may be closed when the engine isoperating. Further, manifold vacuum is considerably higher than thesecond threshold, Threshold_V, represented by line 609. Reservoir vacuum(plot 608) may increase prior to t1, as air is drawn from the vacuumreservoir into the intake manifold. By t1, reservoir vacuum may besubstantially the same as manifold vacuum. Furthermore, at idle, theCMCV may not be adjusted and may be retained in an open position,thereby, the vacuum actuator controlling the CMCV may be in an “OFF”position until t1. Further, without an actuation, the position sensormay not indicate a change (plot 604).

At t1, engine speed may increase initially as the vehicle starts movingand may stabilize later at a lower speed. As an example, a vehicleoperator may depress an accelerator pedal and engine speed may increaseinitially in response to the change in position of the acceleratorpedal. Simultaneously, engine load may increase slightly between t1 andt2. In response to the change in accelerator pedal position, the intakethrottle may be opened and manifold vacuum may decrease between t1 andt2. To enable improved combustion and burn rates, the CMCVs may beactuated to a mostly closed or closed position (plot 606). The actuationand resulting change in position of the CMCVs is indicated by theposition sensor at t1. Further, since vacuum in the vacuum reservoir ishigher than the manifold vacuum at t1, actuation of the vacuum actuatordraws vacuum from the vacuum reservoir and not from the intake manifold.Consequently, vacuum in the vacuum reservoir decreases between t1 and t2due to the sustained actuation of the vacuum actuator.

At t2, in response to a tip-in, engine speed increases significantlyalong with a corresponding increase in engine load. As such, the intakethrottle may be wide open and manifold vacuum decreases considerably,and substantially below line 609 (Threshold_V), due to the increase inmanifold pressure. At t2, the vacuum actuator may be deactivated and theCMCVs may be moved to an open position to enable a desired higher airflow into the intake in response to the tip-in. Accordingly, theposition sensors indicate a change in position at t2. The tip-in eventmay be followed by a decrease in engine speed and engine load, as thevehicle speed stabilizes. Further, between t2 and t3, the vacuumactuator may be actuated for a short period to move the CMCVs into aslightly closed, or mostly closed position. Accordingly, reservoirvacuum may decrease between t2 and t3. As such, the decrease inreservoir vacuum may also be due to leakage flow during the sustainedactuation. Further, as the CMCV is deactivated and the actuator iscommanded OFF, at t3, reservoir vacuum decreases below the firstthreshold, Threshold_P as represented by line 607. Further, thecontroller may set a flag to indicate low vacuum in the reservoir.

At t4, the vacuum actuator may be actuated to activate the CMCVs to amore closed position. However, since the reservoir vacuum is belowThreshold_P and cannot supply the requisite vacuum to actuate the vacuumactuator, the CMCVs may not change position (plot 604) at t4. Further,the controller may not indicate actuator degradation based on the lackof responsiveness of the CMCVs since reservoir vacuum is determined tobe lower than the first threshold, Threshold_P (line 607).Alternatively, when the controller sets the flag at t3 to indicate lowvacuum in the vacuum reservoir, as in reservoir vacuum being below thefirst threshold, Threshold_P (line 607), the controller may additionallypreclude the command to the vacuum actuator at t4.

Between t4 and t5, the vehicle may slow down, and consequently, enginespeed may decrease along with engine load. Further, at t5, idlingconditions may resume such that engine speed is at idle speed and theengine load is nominal. As an example, the vehicle may be idling at astop light. In response to the idling conditions, the intake throttlemay be closed resulting in an increase in manifold vacuum. Between t5and t6, manifold vacuum increases significantly above Threshold_V, andthe intake manifold supplies vacuum to the vacuum reservoir enabling arise in reservoir vacuum to higher than the first threshold, Threshold_P(line 607). At t6, reservoir vacuum may be substantially the same asmanifold vacuum. At t6, engine speed and engine load may increase again.In response to the increase in engine speed, manifold vacuum may reduceconsiderably. Further, the vacuum actuator may be commanded to close (oractivate) the CMCVs at t6. In response to this command, vacuum may besupplied from the vacuum reservoir to the vacuum actuators resulting ina decrease in reservoir vacuum. The position sensors indicate the changein position of the CMCVs at t6.

At t7, another tip-event may occur whereupon the intake throttle may beopened wide leading to a significant reduction in manifold vacuum.Herein, manifold vacuum may decrease below Threshold_V (line 609).Simultaneously, the CMCV actuators may be activated to adjust the CMCVsto their open position. At t8, engine speed and load decrease as thetip-in event may end and the vehicle may be traveling at steady speed.To enable an improved burn rate, the CMCV actuators may be commanded toclose the CMCVs. However, the position sensors do not indicate a changein position in response to the command, at t8. Estimation of reservoirvacuum indicates that the vacuum reservoir has sufficient vacuum (higherthan Threshold_P, line 607). Thus, the controller indicates a degradedactuator (or stuck CMCV) in response to the lack of responsiveness ofthe vacuum actuated valve and the level of vacuum fill in the vacuumreservoir being higher than the first threshold, Threshold_P (plot 602).

As will be appreciated, the above examples include diagnosingdegradation of vacuum actuators such as CMCV actuators and/or vacuumactuated valves such as CMCVs. The methods and routines described hereinmay also be utilized for other vacuum actuators and/or vacuum actuatedvalves.

Thus, an example method may comprise estimating a total amount of vacuumfill level in a vacuum reservoir in an engine, actuating a vacuumactuated valve, and if the vacuum actuated valve does not move inresponse to the actuating, indicating degradation of the vacuum actuatedvalve when the vacuum fill level is higher than a threshold, and notindicating degradation of the vacuum actuated valve when the vacuum filllevel is estimated to be lower than the threshold. The method mayfurther comprise setting a first diagnostic code in response toindicating degradation of the vacuum actuated valve. In response todetermining that the vacuum fill level is lower than the threshold, themethod may also include deactivating the vacuum actuated valve until thevacuum fill level increases to the threshold. The vacuum actuated valve,in one example, may be positioned downstream of an intake throttle in anintake passage of the engine. Further, the vacuum fill level may beestimated based upon flow of air into and out of the vacuum reservoir inresponse to one or more of an actuation of the vacuum actuated valve,leakage during the actuation, and aspirator suction flow. Flow of airinto the vacuum reservoir may be based on a number of successiveactuations of the actuator and a leakage during each actuation of theactuator, and outflow of air from the vacuum reservoir may include airdrawn from the vacuum reservoir by an aspirator.

In this way, degradation of a vacuum actuator may be more reliablydetermined. Vacuum fill in the vacuum reservoir that supplies vacuum tothe vacuum actuator may be monitored in a simple manner by estimatingflow of air into and out of the vacuum reservoir during certainconditions. By estimating vacuum in the vacuum reservoir, erroneousindications of degradation in the vacuum actuator or vacuum actuatedvalve may be reduced. As such, a lack of movement in the vacuum actuatedvalve or vacuum actuator may be attributed to insufficient vacuum fillin the vacuum reservoir. By lowering a likelihood of erroneousindications of degradation, unnecessary and costly diagnostics of thevacuum actuators may also be avoided. Overall, maintenance expenses maybe reduced and customer satisfaction may be improved.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory and may be carried outby the control system including the controller in combination with thevarious sensors, actuators, and other engine hardware. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example embodiments described herein, butis provided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. Further, thedescribed actions, operations and/or functions may graphically representcode to be programmed into non-transitory memory of the computerreadable storage medium in the engine control system, where thedescribed actions are carried out by executing the instructions in asystem including the various engine hardware components in combinationwith the electronic controller.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

1. A method, comprising: indicating degradation of a vacuum actuatorbased on an estimate of flow of air into and out of a vacuum reservoir,the estimate based on flow of air generated via each of an aspirator inan intake system, an actuation of the vacuum actuator, and leakageduring the actuation of the vacuum actuator.
 2. The method of claim 1,wherein degradation of the vacuum actuator is indicated when vacuum fillin the vacuum reservoir based on the estimate of flow of air is higherthan a first threshold and when a position of the vacuum actuator doesnot change when actuated.
 3. The method of claim 2, further comprisingnot indicating degradation of the vacuum actuator when vacuum fill inthe vacuum reservoir based on the estimate of flow of air is lower thanthe first threshold and when the position of the vacuum actuator doesnot change when actuated.
 4. The method of claim 1, wherein the vacuumreservoir is an intake manifold runner control reservoir, and whereinthe vacuum actuator actuates a charge motion control valve.
 5. Themethod of claim 1, wherein the aspirator draws air from the vacuumreservoir, the actuation of the vacuum actuator flows air into thevacuum reservoir, and leakage during the actuation of the vacuumactuator flows air into the vacuum reservoir.
 6. The method of claim 5,wherein flow of air via the actuation of the vacuum actuator is based ona calibrated value, the calibrated value being a first portion of airflowing into the vacuum reservoir per actuation of the vacuum actuator.7. The method of claim 6, wherein flow of air via leakage during theactuation of the vacuum actuator is based on a leakage rate, the leakagerate determined by calculating a second portion of air flowing into thevacuum reservoir over a given duration during sustained actuation of thevacuum actuator.
 8. The method of claim 7, wherein the flow of airgenerated via the aspirator is a function of each of manifold vacuum andvacuum consumed by one or more vacuum consumption devices other than thevacuum actuator.
 9. The method of claim 8, wherein the vacuumconsumption devices include one or more of a brake booster and a fuelvapor canister.
 10. A method, comprising: estimating an amount of vacuumfill level in a vacuum reservoir in an engine; actuating a vacuumactuated valve; and if the vacuum actuated valve does not move inresponse to the actuating, indicating degradation of the vacuum actuatedvalve when the amount of vacuum fill level is higher than a threshold;and not indicating degradation of the vacuum actuated valve when theamount of vacuum fill level is estimated to be lower than the threshold.11. The method of claim 10, further comprising setting a firstdiagnostic code in response to indicating degradation of the vacuumactuated valve.
 12. The method of claim 11, further comprising, inresponse to determining that the amount of vacuum fill level is lowerthan the threshold, deactivating the vacuum actuated valve until theamount of vacuum fill level increases to the threshold.
 13. The methodof claim 12, wherein the vacuum actuated valve is positioned downstreamof an intake throttle in an intake passage of the engine.
 14. The methodof claim 12, wherein the amount of vacuum fill level is estimated basedupon flow of air into and out of the vacuum reservoir in response to oneor more of an actuation of the vacuum actuated valve, leakage during theactuation, and aspirator suction flow.
 15. A system, comprising: anengine with a cylinder, the cylinder fluidically communicating with anintake passage via an intake manifold; a charge motion control valvepositioned in the intake passage downstream of an intake throttle; anactuator that actuates the charge motion control valve between an openposition and a closed position; a vacuum reservoir fluidicallycommunicating with each of the actuator, an aspirator, and the intakemanifold; and a controller with computer-readable instructions stored innon-transitory memory for: actuating the charge motion control valve viathe actuator; and indicating degradation of the actuator if the chargemotion control valve remains motionless in response to the actuatingwhen an amount of air fill in the vacuum reservoir is lower than athreshold.
 16. The system of claim 15, wherein the controller includesfurther instructions for disabling the actuator and the charge motioncontrol valve upon indication of degradation.
 17. The system of claim15, wherein the amount of air fill in the vacuum reservoir is estimatedbased on an inflow and an outflow of air from the vacuum reservoir. 18.The system of claim 17, wherein the inflow of air into the vacuumreservoir is based on a number of successive actuations of the actuatorand a leakage during each actuation of the actuator, and wherein theoutflow of air from the vacuum reservoir includes air drawn from thevacuum reservoir by the aspirator.
 19. The system of claim 15, whereinthe controller includes further instructions for indicating low vacuumin the vacuum reservoir when the amount of air fill in the vacuumreservoir is estimated to be higher than the threshold.